Comunidades vegetais em inselberg: aspectos florísticos e funcionais

Abstract

Inselbergs are monolithic mountains or groups of them, whose geological formation consists especially of granitic and gneiss rocks. They are distributed mainly in tropical and subtropical regions, less common in temperate regions. Generally, the flora and vegetation of inselbergs are clearly distinguished from the surrounding matrix, due to harsh environmental filters, such as high daily temperature variations, constant winds, low retention of water and overheated soils. These factors help to explain the high degree of floristic specificity, in which are found morphological, anatomical and reproductive adaptations, considered advantageous to the survival of plants in these environments. In the first chapter, we sought to describe the plant communities in an inselberg located in the Mucuri Valley, northeast Minas Gerais, throughfloristic inventory, physiognomic characterization and life-form spectrum. A total of 88 species of vascular plants were recorded (belonging to 36 families), of which six were new species to science and four were new records for Minas Gerais state. The family with the highest number of species was Bromeliaceae (10 spp.), followed by Cyperaceae (seven spp.), Orchidaceae and Poaceae (six spp. each). The biological spectra indicated the predominance of phanerophytes (34 spp.), followed by hemicryptophytes (23 spp.) and chamephytes (14 spp.). It was observed high endemism rate and influence of other biomes on the local florastudied. In addition, it was found that the habitats described in this work were determined by specific plant community composition and variable degrees of environmental stress. In the second chapter, we evaluated the importance of CSR (competitiveness:stresstolerance: ruderalism) ecological strategies in different habitat types on the inselberg, testedfor a connection between habitat structure and functional traits, and compared the variation in functional traits between native and an exotic species. We found a relatively high diversity of ecological strategies, but most species lied between the S and C strategy. The invasive specieswas functionally distinctive from native communities, with the predominance of traits associated with ruderalism. We also found that, most functional traits significantly correlated with at least one environmental parameter of the habitats, highlighting the role ofenvironmental filters in structuring plant communities in this heterogeneous environment. Yet, because the habitats are under different environmental conditions, and have different resource availability, some of them were more susceptible to biological invasion than others. The results of this Master thesis therefore increase our understanding regarding the composition and structure of inselberg plant communities and provides insights into the dynamics of biological invasion, a strong threat to these environments. We then argue that theuse of broader approaches, both qualitative and quantitative, are fundamental to the development of conservation strategies and management of the unique vegetation on granitic and gneiss rock outcrops.